Display devices provided in electronic devices such, as television sets, personal computers, cellular phones, and digital cameras that have been used in very large numbers in recent years are usually fabricated by using a substrate from glass or the like as a base, and a display device is produced by disposing circuit elements, control elements, and color filters on this substrate.
For example, a liquid crystal display device is provided with a transparent substrate such as glass and color filters formed on the transparent substrate. By providing the color filters, it is possible to colorize the display light. Therefore, a liquid crystal display device provided with color filters can display color images. The transparent substrate is disposed on the display surface side and color filters are disposed on the inner surface side of the liquid crystal display device.
A light-blocking film for increasing the contrast of display images is usually disposed between the color filters of different colors. For example, a thin metal film can be used as the light-blocking film. However, since metals typically have a high reflectance, when the display device is viewed from the substrate side where the color filters are provided, the ambient light, reflected by the light-blocking film constituted by the thin metal film can decrease the contrast of displayed images.
A method by which a film having a refractive index between the refractive index of the transparent substrate and the refractive index of the metal light-blocking film is provided between the transparent, substrate and the metal light-blocking film has been suggested as a means for resolving the aforementioned problem (see, for example, Patent Document 1). In Patent Document 1, glass is used as a material of the transparent, substrate, a transparent inorganic thin film is used as film capable of preventing the reflection, and TiO (titanium oxide) is disclosed as an example of material for the transparent inorganic thin film. Further, Cr (chromium) is disclosed as a material for the metal light-blocking film.    Patent Document 1: Japanese Patent Application Laid-open No. HS-196809
However, the research conducted by the inventors has revealed that even when the transparent, inorganic thin film is arranged, between the transparent substrate and the metal light-blocking film, as descried in the above-mentioned Patent Document 1, external light reflection occurs at the boundary of the transparent substrate and the transparent inorganic thin film and at the interface between the transparent inorganic thin film and the metal light-blocking film.
This reflection occurs apparently because the layered structure based on the above mentioned Patent Document 1 is configured by stacking an air layer (refractive index: 1), a glass layer (refractive index: 1.5), a TiO layer (refractive index: 2.35), and a Cr layer (refractive index: 3.08) and includes a plurality of layers having intermittently different refractive indexes. Light reflection also occurs at the boundary between media when light is transmitted between media with different refractive indexes, and the reflectance of light incident on the boundary between media is determined by the ratio of the second power of the difference in refractive index between the media and the second power of the sum of the refractive indices. Therefore, where the refractive indexes of layers differ intermittently, reflection of light caused by the difference between the refractive index of the transparent substrate and the refractive index of the transparent inorganic thin film occurs at the boundary between the transparent substrate (glass) and the transparent inorganic thin film (TiO) and reflection of light caused by the difference between the refractive index of the transparent inorganic thin film and the refractive index of the metal light-blocking film occurs at the interface between the transparent inorganic thin film (TiO) and the metal light-blocking film (Cr). As a result, sufficient light reflection preventing effect cannot be obtained.
Further, where the transparent inorganic thin film is disposed on the entire transparent substrate, as in the configuration described in Patent Document 1, the display light generates new reflected light not only in the region where the metal light-blocking film is disposed, but also in the pixel region through which the display light is transmitted. Therefore, the amount of reflected light can be, as a whole, even increased.
Where the amount of reflected light increases, when the light inherently used as the display light (for example, light emitted from the backlight of the liquid crystal display device) and the light created by the reflection of external light are mixed, the display light that should be inherently used is greatly inhibited. For example, contrast in a brightly lit room is decreased and display quality is degraded.